Battery thermal mitigation venting

ABSTRACT

A battery pack for a vehicle electrical system includes a casing for receiving one or more battery modules. The battery modules are insertable into a casing of the battery pack. Additionally, the battery modules may include cooling plate to cool the battery module and provide coolant to another battery module in response to a triggering event. Additionally, the battery modules may include a top cover with a frangible insulating material to further thermally insulate one battery module from another battery module and allow gasses and active material to escape the battery module in response to a triggering event. The battery pack may additionally be configured with vents for venting the gases and active material, such as those generated by a battery module in a thermal runaway event. Additionally, the battery modules may include a heat shield to direct vented gases and active material away from a cabin of a vehicle.

BACKGROUND

Many vehicles in operation today are powered, at least in part, byelectrical systems. To provide sufficient electricity to power an entirevehicle, the electrical system typically includes batteries configuredwith multiple cells. While battery technology is improving, batteriesare still prone to failure. Under certain conditions, battery failuremay lead to thermal runaway of one or more cells. The increase in thenumber of cells may increase a risk of a cell in thermal runawaypropagating heat to nearby cells, triggering a chain reaction andcausing additional cells to enter thermal runaway.

BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description is described with reference to the accompanyingfigures. In the figures, the left-most digit(s) of a reference numberidentifies the figure in which the reference number first appears. Theuse of the same reference numbers in different figures indicates similaror identical components or features.

FIG. 1 is an illustration of an autonomous vehicle including one or morebattery packs configured with thermal runaway mitigation systems, inaccordance with embodiments of the disclosure.

FIG. 2 is a perspective view of an example battery pack of an electricalsystem configured to provide power to a vehicle, in accordance withembodiments of the disclosure.

FIG. 3 is across section view of the example battery pack of FIG. 2taken along line 3-3 in FIG. 2.

FIG. 4 is across section view of the example battery pack of FIG. 2taken along line 4-4 in FIG. 2.

FIG. 5 is a close-up view of a battery pack with two battery modulesinserted therein, the close-up view illustrating fluid paths used duringa thermal runaway event, in accordance with embodiments of thedisclosure.

FIGS. 6A-6C are illustrations of example battery module cooling plateswith cooling channels. FIG. 6A is perspective view of a laminatedcooling plate configuration. FIG. 6B illustrates close-up views ofexample cross-sections of the cooling plates and cooling channels. FIG.6C is a perspective view of an illustrative thermal runaway mitigationregion formation technique.

FIG. 7 is an illustration of an example battery pack configured with aplurality of exhaust vents, in accordance with embodiments of thedisclosure.

FIG. 8 is an illustration of an example battery pack configured with aheat shield, in accordance with embodiments of the disclosure.

FIG. 9 depicts an example process for mitigating a thermal runaway eventin a battery pack.

FIG. 10 depicts an example process for mitigating a thermal runawayevent in a battery pack.

DETAILED DESCRIPTION

As discussed above, while battery technology is improving, batteries arestill prone to failure, and under certain conditions, may lead tothermal runaway of one or more cells. The increase in the number ofcells may increase a risk of a cell in thermal runaway propagating heatto nearby cells, triggering a chain reaction and causing additionalcells to enter thermal runaway.

This application relates to techniques for improving thermal runawaymitigation for batteries, such as may be used in a vehicle electricalsystem. In order to mitigate battery thermal runaway, in some examples,a battery system of a vehicle may include one or more cooling elementsconfigured to expel coolant onto one or more energy storage cells thathave entered thermal runaway. In some examples, a battery system of avehicle may include one or more heat shields and/or vents to direct hotgas or other material expelled from an energy storage cell in thermalrunaway away from other energy storage cells. These and other techniquesmay be used to mitigate propagation of thermal runaway from one energystorage cell to other energy storage cells of the battery system.

The vehicle described herein may include a vehicle that is powered inwhole or in part by one or more batteries. Although primarily discussedin the context of powering an autonomous vehicle, the methods,apparatuses, and systems described herein may be applied to providingpower to a variety of systems (e.g., a sensor system or a roboticplatform), and are not limited to autonomous vehicles. In anotherexample, the techniques may be utilized in an aviation or nauticalcontext, as a distributed storage system, a battery backup system, or inany system powered by the one or more batteries.

According to some examples, a vehicle electrical system may include aplurality of batteries configured in one or more battery packs. In someexamples, a battery pack may include multiple battery modules (e.g.,groups of energy storage cells, battery subsystems, etc.). In someexamples, a battery pack may include multiple stacked battery modules.The battery pack may include a casing configured to secure the batterymodules in place in the vehicle. The casing may be made of a metalmaterial (e.g., aluminum, steel, titanium, etc.), a plastic material(e.g., polymer, etc.), a ceramic material, a composite material (e.g.,fiberglass, carbon fiber, Kevlar, etc.), or a combination of theforegoing or other materials.

The battery pack may include multiple battery module bays, each batterymodule bay being configured to house a battery module. In some examples,each battery module bay may include a pair of rails or other supports onopposing sides of an interior of the casing to support the respectivebattery module. The pairs of rails may be configured to connect tocouplers on opposing sides of a battery module (e.g., exterior surfaceof a battery module housing).

In some examples, at least some of the battery module bays may include aspace surrounding at least a portion of a battery module. The space mayinclude an air gap between a top of a first module and a bottom side ofa second module. The air gap may act as a barrier to heat transferbetween the first and second modules. The air gap may act as a channelto expel gas, active material, and or expelled coolant during a thermalrunaway event. In some examples, the space may extend to a side portionof the respective battery module. The space may be bounded, at least inpart, by the pairs of rails associated with the first and second modules(e.g., pairs of rails to which the first module and the second moduleare coupled). In some examples, the pairs of rails may provide a barrierto prevent or restrict passage of air between the respective spacesadjacent the sides of the respective battery modules. In such cases, therails may be configured to substantially thermally insulate a firstbattery module bay from a second battery module bay. In such examples,the pairs of rails may provide a barrier configured to preclude hotgases produced by a battery module, such as in thermal runaway, fromsubstantially affecting another battery module.

In some examples, the battery module may include a battery modulehousing. The battery module housing may include a cover (or top), one ormore sidewalls, and a base (or bottom). The cover, the side wall(s),and/or the base may comprise a metal, ceramic, plastic, compositematerial, or a combination thereof. Each of the cover, the side wall(s),and the base may be made of a same or different material from oneanother. In at least one example, the cover may comprise a sheet ofstainless-steel material. In some examples, some or all of the batterymodules may include a heat shield and/or insulating material disposedproximate or adjacent to the cover, the side wall(s), and/or the base.In some examples, the heat shield and/or insulating material maycomprise mica (for example, phlogopite, muscovite, or other mica groupphyllosilicates), silicone rubber, Teflon, ceramic, ceramic compounds,aerogel, or other thermally insulating or reflecting material. In someexamples, the heat shield and/or insulating material, when provided, maybe laminated, glued, or otherwise affixed to the cover the side wall(s),and/or the base. In some examples, heat shield materials may comprisemultiple layers of the same or different material (e.g., two layers ofmica may be laminated together, a layer of mica may be laminated to alayer of Teflon, or combinations thereof). In some examples, the heatshield may comprise multiple layers of the same or different materialwhere a layer has a different configuration than another (e.g., a firstlayer of mica being a solid sheet may be laminated to a second layer ofmica having a hole or a plurality of holes creating a heat shield withdifferent thicknesses (e.g., thinner at locations corresponding to thehole or plurality of holes in the second layer than other locationscorresponding to both the first and second layers)). In some examples,the cover, the side wall(s), and/or the base may be configured tosubstantially thermally insulate a respective battery module fromanother battery module situated adjacent (e.g., above or below) therespective battery module. In some examples, at least two of the sidewall(s) of the battery housing may be configured with couplersconfigured to receive (or be received by) rails, such as those describedabove. In some examples, one side wall of the battery may be configuredwith a coupler to receive a rail, and an opposing side wall may beconfigured with a rail to couple to a coupler of the casing of thebattery pack.

In some examples, the battery housing may enclose a plurality of cells,for example energy storage cells. In some examples, the battery modulesmay be configured to vent gases, such as gases emitted from one or moreof the plurality of cells. In such examples, the gases may vent out ofthe battery module via one or more battery module vents. In someexamples, the gases may vent from an interior compartment of the batterymodule into the space surrounding at least the portion of the batterymodule. In some examples, each battery module bay of the battery packmay include one or more vents (e.g., casing vents) for venting gasesoutside of the casing. The casing vent(s) may be configured tosubstantially equalize pressure between the battery module bay (e.g.,space containing gas) and an atmosphere outside the casing. In someexamples, the casing vent(s) may comprise a breathable material (e.g.,membrane) configured to filter contaminants from gases exiting thevent(s) and/or to prevent contaminants from entering the battery pack.In some examples, the casing vent(s) may be configured to be sealedduring normal operation and to “blow out” (i.e., release pressure) suchas when subjected to a threshold pressure differential between thebattery module bay and the atmosphere outside the vehicle. The batterymodule vent(s) and the casing vent(s) may prevent a battery module fromover-pressurizing and/or over-heating, such as in the case of a cellfailure and/or thermal runaway.

In some examples, the plurality of cells may be configured in multiplerows of cells. In some examples, the cells in a row of cells may be inparallel. In some examples, the cells in a row of cells may beconfigured in series. In some examples, each cell in a roll of cells maybe configured with a positive polarity on a first side of the batterymodule and a negative polarity on a second side of the battery moduleopposite the first side.

FIG. 1 is an illustration of an example autonomous vehicle 100 havingone or more batteries configured with thermal runaway mitigation systemsto provide power to operating systems of the autonomous vehicle, inaccordance with examples of the disclosure.

In the illustrated example, the vehicle 100 includes a first driveassembly 102A and a second drive assembly 102B (collectively “driveassemblies 102”) coupled to a body 104. Each of the drive assemblies 102in this example includes multiple vehicle systems. For example, thefirst drive assembly 102A in this example includes a first battery withthermal mitigation system 106A and a first cooling system 108A, and thesecond drive assembly 102B includes a second battery with thermalmitigation system 106B and a second cooling system 108B. The firstbattery with thermal mitigation system 106A and the second battery withthermal mitigation system 106B may be referred to collectively as“batteries 106,” and the first cooling system 108A and the secondcooling system 108B may be referred to collectively as “cooling systems108.” Each of the first drive assemblies in this example also includeone or more motor(s) 110 and one or more other systems 112. In someexamples, motor(s) 110 comprise or are part of a propulsion system ofthe vehicle. By way of example and not limitation, the other system(s)112 may comprise a steering system, a braking system, a suspensionsystem, related controls and actuators for the forgoing systems,electronics related to supplying power from the one or more batteries106 to one or more other components or systems of the drive assemblies102 and/or the body 104. In some examples, the drive modules may alsoinclude exterior lighting, body panels, facia, and/or sensors.

The body 104 in this example includes one or more computer systems 114to control operation of one or more systems of the vehicle 100. Forinstance, in the case of an autonomous vehicle, the computer system(s)114 may include one or more processors and memory and may be configuredto control the vehicle 100 to, among other things, receive and processsensor data from one or more sensors and to plan a route for the vehiclethrough an environment.

In some examples, the cooling systems 108 may be used to cool thebatteries 106 by circulating coolant from the cooling systems 108 toand/or through the batteries 108 via one or more fluid circuits totransfer thermal energy away from the batteries 106 to at least one ofthe cooling systems 108. The cooling systems 108 may also be used tocool one or more other systems of the vehicle 100. For instance, in someexamples the first cooling system 108A and/or the second cooling system108B may comprise a heating ventilation and air conditioning (HVAC)system used to cool a passenger compartment of the vehicle. In examples,in some examples the first cooling system 108A and/or the second coolingsystem 108B may provide cooling to a motor 110 of the first driveassembly 102A and/or the second drive assembly 102B. By way of exampleand not limitation, the cooling systems 108 may include one or morereservoirs, circulation systems, heat exchangers, condensers,compressors, valves, and/or controllers to provide cooling and/orthermal management to various components and/or systems of vehicle 100.

As shown in FIG. 1, the first battery with thermal mitigation system106A includes a battery pack 116 shown in the detail view outlined indashed lines. While not shown in FIG. 1, the second battery with thermalmitigation system 106B also includes a battery pack 116. Thus, in theillustrative example of FIG. 1, the vehicle 100 includes two batterypacks. In other examples, the vehicle 100 may include a greater orlesser number of battery packs.

Each of the battery packs 116 may be configured with one or more batterymodules 118(1), 118(2), . . . 118(N) (collectively “battery modules118”), where N is any integer greater than or equal to 1 (e.g.,batteries, battery subsystems, etc.). In the illustrative example, eachof the battery packs 116 include six battery modules 118 configured in astack. In other examples, the battery packs 116 may include a greater orlesser number of battery modules 118. Additionally, in other examples,the battery module(s) 118 may be configured differently, such assubstantially horizontally, substantially vertically, rotated 90 degreesfrom that shown in FIG. 1, and/or in any other configuration.

In some examples, the battery module(s) 118 may be coupled to a casing120 of the battery pack 116. The casing 120 may include a metal material(e.g., aluminum, steel, titanium, etc.), a plastic material (e.g.,polymer, etc.), a ceramic material, a composite material (e.g.,fiberglass, carbon fiber, Kevlar, etc.), or a combination thereof. In atleast one example, the casing 120 may include a metal material, formedvia an extrusion process. In some examples, the casing 120 may include abase, a cover, and four side walls including a front side wall, a rearside wall, a right side wall and a left side wall (e.g., first sidewall, second side wall, third side wall, fourth side wall). Althoughillustrated as a cross section, with one side of the casing 120 removed,the casing 120 of the battery pack 116 may be configured to envelope thebattery modules 118 on all sides. In some examples, the casing 120 ofthe battery pack 116 may be configured to be substantially water proofand/or water resistant.

In some examples, each battery module 118 may be configured to couple toa casing attachment mechanism. In some examples, the casing attachmentmechanism may include pairs rails 122(1), 122(2), . . . 122(M)(collectively “rails 122”), where M is any integer greater than or equalto 1. The number of pairs of rails M may or may not be equal to thenumber of battery modules N. The rails 122 may include a metal material,a ceramic material, a composite material, a plastic material, or acombination of the foregoing. The rails 122 may include the samematerial or a different material than the casing 120. In some examples,the rails 122 may be disposed on an internal surface of the front sidewall (e.g., first side wall) and the rear side wall (e.g., second sidewall) in a substantially horizontal configuration. In some examples, therails 122 may extend from a first end, substantially situated at theright side wall (e.g., third side wall), to a second end, substantiallysituated at the left side wall (e.g., fourth side wall). In suchexamples, the rails 122 may substantially extend a length of the casing120.

The rails 122 may be configured to connect to couplers on opposing sidesof a battery module 118 (e.g., exterior surface of a battery housing).In some examples, the rails 122 may include a coating. The coating mayinclude rubber, polyurethane, nylon, Teflon, silicone, polypropylene,polyethylene, or the like. In some examples, the coating may beconfigured to increase and/or decrease a frictional component betweenthe rails 122 and the couplers of the battery modules 118. In someexamples, the coating may be configured to assist in substantiallythermally isolating heat of one battery module (e.g., battery module118(1)) from affecting another battery module (e.g., battery module118(2). In such examples, the coating may assist in preventing gases,such as those emitted from a battery module during thermal runaway, frompropagating to the other battery module.

In the illustrative example, the rails 122 are configured in pairs ofrails 122 disposed on opposite internal surfaces of the battery pack116. Each of the pairs of rails 122 can be connected to couplers (e.g.,module couplers, module attachment mechanisms, etc.) on opposite sidesof a battery module 118. In some examples, the casing attachmentmechanism may include a casing coupler disposed on an internal surfaceopposite a respective rail 122. In such examples, a battery module 118may be configured to couple to a casing coupler via a rail disposed onthe battery module 118 on one side and a rail 122 of the battery pack116 via a module coupler on the other side. In some examples, theopposing internal surfaces of the battery pack 116 may includealternating rails 122 and casing couplers. For example, a casing couplermay be disposed between two rails. In some examples, the opposinginternal surfaces of the battery pack 116 may include casing couplers ona first internal surface and rails 122 on a second internal surface, thefirst internal surface and the second internal surface being oppositeinternal side walls.

In some examples, each rail 122 may be disposed at a substantially equaldistance vertically from one another. In such examples, each batterymodule 118 may be spaced a substantially similar vertical distance fromanother battery module 118 inserted into the casing 120. For example,after insertion, such as via sliding the couplers of the battery module118 along the rails 122, a bottom side of a first battery module 118(1)may be spaced a distance from a top side (e.g., cover) of a secondbattery module 118(2). The distance may provide an air gap configured toprevent direct thermal conduction between the first battery module118(1) and the second battery module 118(2).

Additionally, in some examples, after insertion, the battery module(s)118 may be secured into the casing via one or more fasteners (e.g.,screws, rivets, pins, snap connectors, latches, spring-type fasteners,etc.) at an end of the rails 122.

In some examples, the coupling of the battery modules 118 in the casing120 via one or more pairs of rails 122 results in a relatively stiff andrigid battery pack 116. The stiffness of the battery pack 116 mayincrease a torsional and/or lateral stiffness of the vehicle 100. Insuch examples, the stiffness of the battery pack 116 may increasevehicle 100 handling, steering, and/or ride characteristics. In at leastone example, one or more battery modules 118 in the battery pack 116 maybe offset from other battery modules 118 in the battery pack 116. Forexample, as illustrated in FIG. 1, the bottom two battery modules 118 inthe battery packs 116 are offset from a vertical stack of four otherbattery modules 118. The offset design of one or more of the batterymodules 118 may additionally increase a stiffness of the battery pack116, further improving torsional and/or lateral stiffness of the vehicle100. In some examples, an increase in the torsional and/or stiffness ofthe vehicle may also minimize vibration of the battery pack 116,reducing the risk of damage to cells of the battery pack which couldlead to thermal runaway. In some examples, the battery module(s) 118 ina battery pack 116 may be configured substantially the same or similarto one another. In such examples, the battery module(s) 118 in a batterypack 116 may be interchangeable. The battery module(s) 118 may include abattery module housing including at least a base and four side walls. Atleast two of the four side walls may be configured with the couplersdescribed above that are configured to slide along the rails 122 in thecasing 120. In some examples, the at least two of the four side wallsmay be configured with a module attachment mechanism configured tocouple to a casing attachment mechanism, such as those described above.In such examples, the casing attachment mechanism may include at least arail or a coupler and the corresponding module attachment mechanism mayinclude the other of the rail or the coupler. In some examples, thebattery module housing may additionally include a cover.

As described above, the battery module housing may comprise a metal, aceramic, a plastic, a composite material, or a combination thereof. Thebase, four side walls, and the cover may comprise a same or similarmaterial. In some examples, the base, the four side walls, and/or thecover may include an insulating material (e.g., mica, silicone rubber,Teflon, etc.). In some examples, those insulating materials may becoupled to (e.g., laminated, glued, etc.) other materials (e.g., metal,ceramic, plastic, or combinations thereof), for example, for structural,protection, and/or durability purposes.

In some examples, the battery housing may enclose a plurality of cellsof the battery module 118. Each cell of the plurality of cells mayinclude a cylindrical cell, a pouch cell, a prismatic cell, a buttoncell, or the like. In some examples, the cells in the plurality of cellsare cylindrical cells. In some examples, the plurality of cells may beseparated from one another by an insulating material. In some examples,the insulating material may comprise an insulating foam (e.g., siliconefoam, silicone potting, etc.). In some examples, the insulating materialdisposed between individual cells of the plurality of cells maysubstantially fill an interstitial space between the cells and maymitigate effects of thermal runaway of a single cell by isolating thecell from other cells proximate thereto. In such examples, theinsulating material may enhance thermal runaway mitigation techniques bythermally isolating the cells from one another.

In some examples, one or more of the cooling systems 108 provide coolantto the battery modules 118 to further improve thermal runawaymitigation. In the illustrated example, coolant is supplied to thebattery modules 118 via a coolant manifold 124 connecting through port126 on a battery module 118. The coolant may be supplied to the coolantmanifold 124 by the first cooling system 108A and/or the second coolingsystem 108B of vehicle 100 via connection port 128.

As discussed above, in some examples the first cooling system 108A andthe second cooling system 108B may be separate systems that are not influid communication with one another. For example, the first coolingsystem 108A may provide coolant to the battery pack 116 of the firstbattery 106A from a first coolant circuit including a first coolantreservoir, and the second cooling system 108B may provide coolant to thebattery pack 116 of the second battery 106B from a second coolantcircuit including a second coolant reservoir. In this example, thebattery packs 116 of the first battery 106A and the second battery 106Bare not in fluid communication with each other.

In other examples, the first cooling system 108A may be in fluidcommunication with the second cooling system 108B. For instance, thefirst cooling system 108A may provide coolant to the battery packs 116of both the first battery 106A and the second battery 106B from a commoncoolant circuit. In this example, the battery packs 116 of the firstbattery 106A and the second battery 106B are in fluid communication witheach other.

Additionally or alternatively, in some examples the first cooling system108A and the second cooling system 108B may be selectively connected ordisconnected. For example, it may be desirable to operate the firstbattery 106A and second battery 106B as separate systems in somecircumstances (e.g., during normal operation), and may be desirable tooperate the first battery 106A and the second battery 106B from a commonsystem in other circumstances (e.g., upon detecting occurrence of athermal runaway event). For example, operating from separate coolingsystems may allow control of the cooling and flowrates of the coolant toeach battery pack 116 based on the status and condition of each batterypack 116 which may result in more efficient cooling. Additionally oralternatively, separate cooling systems provides a level of redundancysuch that a failure in a first cooling system does not affect a secondcooling system, and may allow the second cooling system to supplysufficient cooling to a battery pack. Additionally or alternatively,providing control to connect or disconnect the cooling systems 108provides flexibility to provide cooling to two or more battery packs 116from a common cooling system or reservoir when needed. For example,during a thermal runaway event, it may be desirable to provideadditional coolant to the battery pack 116 experiencing the thermalrunaway event.

Additionally or alternatively, some examples contemplate that thecooling systems 108 may provide a circulation path for the coolant. Forexample, cooling systems 108 may provide coolant to an inlet side of abattery pack 116, where coolant may be circulated to one or more coolingelements disposed within one or more modules of the battery pack 116,and may be returned to the cooling system 108 through an outlet side,for example, on an opposite side of the battery pack 116.

Additionally, to further improve thermal runaway mitigation forbatteries, the battery modules 118 may be configured to vent gases, suchas gases emitted from one or more of the plurality of cells. In someexamples, gases may vent out of an uncovered surface of the batterymodules 118. In such examples, the battery modules 118 may not include acover, and gas may be free to vent from the plurality of cells into aspace between modules and/or between a module and an interior surface ofthe casing. In some examples, the gases may vent out of the batterymodule through the cover. For example, if the gas exhausted, forexample, during a thermal runaway event, the gas and/or active materialmay breach the top and be vented into a gap between adjacent modules.

In some examples, each battery module bay of the battery pack mayinclude one or more vents (not shown in this figure) for venting gasesoutside of the vehicle. As discussed above, the vent(s) may beconfigured to substantially equalize pressure between the battery modulebay (e.g., space containing gas) and an atmosphere outside the vehicle.In some examples, the casing vent(s) may comprise a breathable material(e.g., membrane) configured to filter contaminants from gases exitingthe casing vent(s). In some examples, the casing vent(s) may beconfigured to blow out (e.g., removed from casing to maximize a pressureequalization), such as when subjected to a threshold pressuredifferential between the battery module bay and the atmosphere outsidethe vehicle. The battery module vent(s) and the casing vent(s) mayprevent a battery module from over-pressurizing and/or over-heating,such as in the case of a cell failure and/or thermal runaway, therebyimproving thermal runaway mitigation of the electrical system.

In some examples, the computer systems 114 controls operation of one ormore systems of the vehicle 100. For instance, in the case of anautonomous vehicle, the computer system(s) 114 may include one or moreprocessor(s) 130 and memory 132 communicatively coupled with the one ormore processor(s) 130 and may be configured to control the vehicle 100to, among other things, receive and process sensor data from one or moresensors and to plan a route for the vehicle through an environment.

In the illustrated example, the vehicle 100 is an autonomous vehicle;however, the vehicle 100 could be any other type of vehicle, such as asemi-autonomous vehicle, or any other system having at least an imagecapture device (e.g., a camera enabled smartphone). Though depicted inFIG. 1 as residing in the body 104 for illustrative purposes, it iscontemplated that the computer systems 114 be accessible to the vehicle100 (e.g., stored on, or otherwise accessible by, memory remote from thevehicle 100, such as, for example, on memory of a remote computerdevice). In some examples, multiple computer systems 114 may be includedon the vehicle 100. In some examples, computer systems 114 may belocated within the body 104, a drive assembly 102, or combinationsthereof.

The processor(s) 130 of the vehicle 100 may be any suitable processorcapable of executing instructions to process data and perform operationsas described herein. By way of example and not limitation, theprocessor(s) 130 may comprise one or more Central Processing Units(CPUs), Graphics Processing Units (GPUs), or any other device or portionof a device that processes electronic data to transform that electronicdata into other electronic data that may be stored in registers and/ormemory. In some examples, integrated circuits (e.g., ASICs, etc.), gatearrays (e.g., FPGAs, etc.), and other hardware devices may also beconsidered processors in so far as they are configured to implementencoded instructions.

Memory 132 is an example of non-transitory computer-readable media.Memory 132 may store an operating system and one or more softwareapplications, instructions, programs, and/or data to implement themethods described herein and the functions attributed to the varioussystems. In various implementations, the memory may be implemented usingany suitable memory technology, such as static random access memory(SRAM), synchronous dynamic RAM (SDRAM), nonvolatile/Flash-type memory,or any other type of memory capable of storing information. Thearchitectures, systems, and individual elements described herein mayinclude many other logical, programmatic, and physical components, ofwhich those shown in the accompanying figures are merely examples thatare related to the discussion herein.

In some instances, memory 132 may include at least a working memory anda storage memory. For example, the working memory may be a high-speedmemory of limited capacity (e.g., cache memory) that is used for storingdata to be operated on by the processor(s) 130. In some instances,memory 130 may include a storage memory that may be a lower-speed memoryof relatively large capacity that is used for long-term storage of data.In some cases, the processor(s) 130 cannot operate directly on data thatis stored in the storage memory, and data may need to be loaded into aworking memory for performing operations based on the data, as discussedherein.

FIG. 2 is a perspective view of an example battery pack 200, such asbattery pack 116, of an electrical system configured to provide power toa vehicle, in accordance with embodiments of the disclosure. The batterypack 200 includes a plurality of battery modules 202, such as batterymodules 118. In some examples, the battery modules 202 in battery pack200 may be configured substantially the same, and thus may beinterchangeable in the battery pack 200. In the illustrative example,the battery pack 200 includes six stacked battery modules 202, thebottom two battery modules 202 being slightly offset from the other fourbattery modules 202. In other examples, the battery pack 200 may includea greater or lesser number of battery modules 202. Additionally, inother examples, the battery modules 202 may be disposed in differentorientations within the battery pack 200. The different orientations mayinclude battery modules being disposed substantially horizontally, bothhorizontally and vertically, vertically with no offset, horizontallyand/or vertically with more and/or different battery modules offset, orthe like.

FIG. 2 also shows casing 204, such as casing 120, with a panel (notshown) removed from an end of casing 204 exposing battery modules 202.In this example, battery modules 202 are connected to coolant manifold208, such as coolant manifold 124, through ports 210, such as ports 126.Coolant manifold 208 may be connected to one or more cooling systems,such as cooling systems 108, of a vehicle, such as vehicle 100 throughconnection port 212 such as connection port 128. In this configuration,FIG. 2 shows outlet side 214 of battery pack 200. However, it isunderstood that coolant may flow in either direction as desired. Forexample, if a triggering event occurs in battery pack 200, coolant maybe expelled into battery pack 200 to mitigate a thermal runaway event.

FIG. 3 is a cross sectional view of the battery pack of FIG. 2, takenalong line 3-3 in FIG. 2. Battery pack 200 includes a plurality ofbattery modules 200. In the illustrated example, the battery modules 202each comprise a cooling element 302 to receive coolant from the coolingmanifold 208 (not shown in this figure). In some examples, coolingelement 302 may receive coolant from a cooling system and may circulatethe coolant through the cooling plate via channels, tubes, passages,cavities, coils, or other features, to remove heat from the batterymodule. In the example of FIG. 3, the cooling element is shown as acooling plate disposed within battery module 202 below a plurality ofenergy storage cells 304 of the respective battery module.

In the illustrative example, the battery pack 200 includes six stackedbattery modules 202, the bottom two battery modules 202 being slightlyoffset from the other four battery modules 202. In other examples, thebattery pack 200 may include a greater or lesser number of batterymodules 202. Additionally, in other examples, the battery modules 202may be disposed in different orientations within the battery pack 200.The different orientations may include battery modules being disposedsubstantially horizontally, both horizontally and vertically, verticallywith no offset, horizontally and/or vertically with more and/ordifferent battery modules offset, or the like.

FIG. 3 also shows casing 204, such as casing 204 housing battery modules202. In some examples, battery modules 202 may be inserted into batterypack 200 and secured to casing 204 via rails 306, such as rails 122. Inthis example, battery module 200(1) may be secured to casing 204 viarails 306(1) and 306(2).

In some examples, the battery module(s) 202 may each be housed in abattery module bay 308 of the battery pack 200. Each battery module bay308, such as battery module bays 308(1) and 308(2) may include a spacein which to house a battery module 202, such as battery modules 202(1)and 202(2), respectively, and a space surrounding at least a portion ofthe battery module 202. The space surrounding the at least the portionof the battery module 202 may provide an air gap 310 between two batterymodules, such as the illustrated space between battery modules 202(1)and 202(2). In some examples, the space surrounding the at least theportion of the battery module 202 may assist in thermally isolating thebattery modules 202 from one another, such as in the event of a batterymodule 202 thermal runaway (e.g., accelerating temperature increase). Inother examples, the space surrounding the at least the portion of thebattery module 202 may assist in triggering a thermal mitigation actionfrom the system.

In some examples, the battery modules 202 may be configured with one ormore vents (not illustrated) to vent gases out of respective batterymodules 202. In some examples, the vent(s) may be disposed along a sidewall of the battery modules 202, extending at least partially along alength of the side wall. In some examples, in the event of a thermalrunaway of one or more cells of a battery module 202, gases and activematerial generated from the thermal runaway may exit the battery modulevia the vent(s).

In some examples, the rails 306 may be configured to substantiallypreclude or limit the gases exiting a battery module, such as batterymodule 202(2) from substantially effecting a second battery module, suchas battery module 202(1), such as by substantially thermally isolating(e.g., insulating) the battery modules 202. In such examples, the rails306(1) and 306(2) may provide a barrier configured to limit gas flowbetween battery module bay 308(2) and battery module bay 308(1).Substantially precluding the hot gases from entering the battery modulebay 308(1), and consequently surrounding battery module 202(1), mayreduce an impact of the thermal runaway of battery module 202(2) on aninternal temperature of battery module 202(1).

FIG. 4 is a cross-sectional view of the battery pack 200 of FIG. 2,taken along line 4-4 in FIG. 2. FIG. 4 shows a view perpendicular to theview shown in FIG. 3. The battery pack 200 includes a plurality ofbattery modules 202 that comprise cooling element 302 and receivecoolant from the cooling manifold 208 (not shown in this figure). FIG. 4shows the cooling element as a cooling plate disposed within batterymodule 202 below a plurality of energy storage cells 304 of therespective battery module.

In the illustrative example, the battery pack 200 includes six stackedbattery modules 202. In other examples, the battery pack 200 may includea greater or lesser number of battery modules 202.

FIG. 4 also shows casing 204, such as casing 204, housing batterymodules 202. In some examples, battery modules 202 may be inserted intobattery pack 200 and secured to casing 204 such that adjacent batterymodules are separated by a space. The space surrounding at least theportion of the battery module 202 may provide an air gap 310 between twobattery modules 202.

In some examples, the space surrounding the battery module 202 mayassist in thermally isolating the battery modules 202 from one another,such as in the event of a battery module 202 thermal runaway (e.g.,accelerating temperature increase). In other examples, the spacesurrounding the at least the portion of the battery module 202 mayassist in triggering a thermal mitigation action from the system.

In some examples, the battery modules 202 may be configured with one ormore vents 408 to vent gases out of respective battery modules 202. Insome examples, the vent(s) 408 may be disposed along a side wall of thebattery modules 202, extending at least partially along a length of theside wall. In some examples, in the event of a thermal runaway of one ormore cells of a battery module 202, gases and active material generatedfrom the thermal runaway may exit the battery module via the vent(s)408.

In some examples, the battery modules 202 may be configured with one ormore troughs 412 to guide fluid away from electronics and out of therespective battery modules 202. In some examples, trough 412 may bedisposed along a side wall of the battery modules 202, extending atleast partially along a length of the respective battery module 202. Insome examples, trough 412 may take the form of a moat, channel, gutter,trench, or combinations thereof, among others. In some examples, in theevent of a thermal runaway of one or more cells of a battery module 202,gases and active material generated from the thermal runaway may exitthe battery module via the trough 412. In some examples, the trough 412may direct gasses and active material to exit the battery module 202through vent 408. In some examples, trough 412 may create a barrierbetween adjacent battery modules 202 to prevent or reduce gases, activematerial, and/or coolant from entering an adjacent module bay 308.Trough 412 may additionally or alternatively be configured to collectand route coolant expelled from a battery module 202 out of the batterypack 200.

Additionally or alternatively, in some examples, trough 412 may beintegrated into one or more of the battery modules 202, for example, asa flange or surface protruding from and/or affixed to one or more edgesof the battery modules 202. In some examples, trough 412 may be formedas a flange or surface protruding from and/or affixed to the an inwardfacing surface of the casing 204.

FIG. 5 is an enlarged view of section 410 of FIG. 4, and shows batterypack 200 with battery modules 202(1) and 202(2) housed within casing 204separated by gap 310. As discussed above, the battery modules 202contain energy storage cells 304 for providing power. For example,battery module 202(2) includes cells 304 while battery module 202(1)includes cells 304(1)-(3). In this illustrative example, the coolingelement 302 of battery module 202(2) comprises a cooling plate 510 withcooling channels 512 as well as a reinforcement plate 514. In thisexample, cooling plate 510 may circulate coolant through coolingchannels 512 and help regulate thermal characteristics of cells 304 ofbattery module 202(2). In some examples, the cooling channels 512 may bein fluid communication with one or more cooling systems, such as coolingsystems 108 to move coolant and heat in and out of cooling plate 510.

In an example where a thermal runaway event occurs in one or more cells,for example, cells 304(1) and 304(2) of battery module 202(1), cells304(1) and 304(2) may over heat and eject gas and/or active material 516(represented as open ended arrows) during the thermal runaway event. Theejected gas and/or active material 516 may leave the cells 304(1)-(2) ata high temperature and/or at a high rate of speed. Upon leaving thecells, the ejected gas and/or active material 516 may impinge on a lowersurface of battery module 202(2). When the ejected gas and/or activematerial 516 reaches a threshold energy level (this may be a combinationof temperature, speed, mass of the ejected gas and/or active material516), the ejected gas and/or active material 516 will trigger a breachin cooling plate 510 to expel coolant 518 (represented by solid arrows)from cooling channels 512. The threshold energy depends on the materialand/or thicknesses of the upper and lower surfaces of the coolingelement, reinforcement plate, and/or heat shield of battery module202(2), and any heat shield and/or, cover of battery module 202(1).

Expelled coolant 518 may mix with ejected gas and/or active material 516to reduce the energy level of ejected gas and/or active material 516 toreduce or mitigate thermal runaway. Additionally or alternatively,expelled coolant 518 may engage (e.g., douse or drench) cells 304(1) and304(2) to further reduce or mitigate thermal runaway. In examples, thereduction in the energy level of ejected gas and/or active material 516may prevent or slow other cells 304, for example, cell 304(3) fromentering thermal runaway.

In examples, while leaving cells 304(1) and 304(2) ejected gas and/oractive material 516 may pass through heat shield 520 of battery module202(1). In examples, heat shield 520 may include an include insulativeproperties. For example, heat shield 520 may provide thermal insulationfrom an adjacent battery module. In examples, heat shield 520 mayprovide electrical insulation from adjacent battery modules or devices.In examples, heat shield 520 may be made of mica, for example,phlogopite, muscovite, silicone rubber, Teflon, ceramics, among others,or combinations thereof.

In examples, heat shield 520 be frangible such that when ejected gasand/or active material 516 pass through heat shield 520, a hole iscreated in heat shield 520 sufficient to allow ejected gas and/or activematerial 516 to pass into gap 310, but without causing ejected gasand/or active material 516 to be directed to other cells 304, forexample, cell 304(3). In this example, heat shield 520 may provide acheck valve functionality where ejected gas and/or active material 516is allowed to leave battery module 202(1), but not reenter an affectother cells 304, for example, cell 304(3).

In examples, heat shield 520 may a thickness based on several factors.For example, the material of the heat shield 520, the distance fromcells 304, the types of cells 304, or combinations thereof, amongothers, may drive the thickness of heat shield 520. In some examples,heat shield may be between about 1 millimeter and about 3 millimetersthick. In some examples, heat shield 520 may be disposed less than about10 millimeters from the cells. For instance, the heat shield 520 may bedisposed adjacent to cells 304 and (e.g., in contact with cells 304),about 3 millimeters away, about 5 millimeters away, about 7 millimetersaway, about 10 millimeters away, or more. In some examples, the distancebetween heat shield 520 and cells 304 may vary within a battery moduleand/or between different battery modules. In some examples, the distancebetween heat shield 520 and cells 304 may depend on a layout and/orconfiguration of the battery module. For example, wire bonds and/orplastic holders, or a lack thereof, disposed above the cells 304 maycause a larger distance or allow a shorter distance between cells 304and heat shield 520.

Additionally or alternatively, in some examples, when heat shield 520 isrelatively closer to cells 304, the thickness of heat shield 520 may berelatively thicker. Conversely, when heat shield 520 is relativelyfurther from cells 304, the thickness of heat shield 520 may berelatively thinner.

In examples, ejected gas and/or active material 516 and expelled coolant518 may be directed from battery pack 200, for example, through gap 310and out vent(s) 408. By removing ejected gas and/or active material 516and expelled coolant 518 from battery pack 200, thermal runaway may befurther mitigated. For example, by removing the ejected gas and/oractive material 516, any residual energy (whether in the form of heat,chemical energy, or other) of the ejected gas and/or active material 516will avoid impinging on other cells 304 or battery modules 202, or otherelectrical equipment contained within battery pack 200. Additionally oralternatively, by removing expelled coolant 518 from battery pack 200,any conductivity contained in expelled coolant 518 either originally, oracquired though interacting with ejected gas and/or active material 516and/or other components of battery pack 200, will avoid shorting orbridging electrical connections in battery pack 200 if expelled coolant518 would otherwise be allowed to pool within battery pack 200.

In some examples, cells 304 may be separated from one another by aninsulating material 522. In some examples, the insulating material 522may comprise an insulating foam (e.g., silicone foam, silicone potting,etc.). In some examples, insulating material 522 disposed between cellsmay substantially fill an interstitial space between the cells and maymitigate effects of thermal runaway of a single cell by isolating thecell from other cells proximate thereto. In such examples, theinsulating material 522 may enhance thermal runaway mitigationtechniques by thermally isolating the cells from one another. Inexamples, the insulating material 522 works with heat shield 520 toprovide thermal protection to cells 304 by creating an insulatingbarrier.

Reinforcement plate 514 may be configured provide structural support tobattery module 202, may provide protection to cooling plate 510, and/orprovide insulation to battery module 202. In examples, reinforcementplate 514 may be configured to be thermally transparent during a thermalrunaway. In examples, reinforcement plate 514 may be configured to formthermal runaway mitigation regions.

In some examples, such as where a battery module is offset from anotherbattery module 202 or where a battery module is not below anotherbattery module 202 (e.g., at the top of a stack of battery modules), acooling element may be extended above the cells of the battery modulebelow. Additionally or alternatively, in some examples, an auxiliarycooling element may be selectively attached to the battery module 202 tocover the area not below another battery module. Additionally oralternatively, in some examples, an auxiliary cooling element may beselectively attached to the casing 204 to cover the area not belowanother battery module.

FIGS. 6A-6C show views of example cooling plates. FIG. 6A shows a bottomview of an illustrative cooling plate 600. Cooling plate 600 may have aninlet 602 configured to receive coolant and an outlet 604 configured toreturn coolant to a cooling system. Cooling plate 600 may also havecooling channels 606 that may be formed by structures 608 and structures610. Cooling plate 600 may have thermal runaway mitigation regions.These thermal runaway mitigation regions may be configured to triggerduring a thermal runaway event, for example, when gas or active materialmeet or exceed a threshold energy level. The trigger may cause therelease of coolant from the cooling channels. In examples, the releasemay be in the form of breaching a surface of the cooling plate, forexample, at a thermal runaway mitigation region. The thermal runawaymitigation regions may be tailored to respond a trigger to delivercoolant to the desired area to mitigate the thermal runaway. Forexample, the thermal runaway mitigation regions may be configured toonly cause a breach when a thermal runaway reaches a threshold energylevel, and may be configured to create a sufficiently sized breach toexpel enough coolant to mitigate the thermal runaway, and maintainsufficient structure to continue to direct the coolant to the desiredarea.

In some examples, thermal runaway mitigation regions may be located atvarious localized locations on the cooling plate and may be formedthrough various techniques. The following are some examples ofconfigurations and techniques usable to create and configure the thermalrunaway mitigation regions.

FIG. 6B shows cutaway views (1)-(7) of illustrative cooling plate crosssections with illustrative thermal runaway mitigation regions. Forexample, cutaway view (1) shows a cooling plate 612 with a thicker uppersurface 614 when compare to lower surface 616. In this example, if theupper and lower surfaces are made from a common material, or a materialwith similar thermal properties, the triggering event would cause lowersurface 616 to breach before upper surface 614 thereby protecting thecells above upper surface 614. In this example, thermal runawaymitigation regions may span lower surface 616.

Cutaway view (2) shows a cooling plate 618 with a thicker upper surface620 when compare to lower surface 622. In this example, if the upper andlower surfaces are made from a common material, or a material withsimilar thermal properties, the triggering event would cause lowersurface 622 to breach before upper surface 620 thereby protecting thecells above upper surface 620. In this example, upper surface 620 iscreated by laminating another layer of the same or different material toform the thicker section. In this example, thermal runaway mitigationregions may span lower surface 622.

Cutaway view (3) shows a cooling plate 624 with cooling channels 606formed by structures 608. In this example, lower surface 626 is thinnerat regions away from structures 608 while lower surface 626 is thickerat structures 608, for example, by the added thickness of layer 628. Inthis example, thermal runaway mitigation regions may span lower surface626 at the regions away from structures 608.

Cutaway view (4) shows a cooling plate 630 with cooling channels 606formed by structures 608. In this example, lower surface 632 is thinnerat regions away from structures 608 while lower surface 632 is thickerat structures 608, for example, by the increased thickness 634. In thisexample, thermal runaway mitigation regions may span lower surface 632at the regions away from structures 608. In this example, the thicknessdifference between lower surface 632 and increased thickness 634 may becreated through various techniques, including, for example, throughhydroforming, welding, additive manufacturing, or other materialdeposition techniques.

Cutaway view (5) shows a cooling plate 636 with cooling channels 606formed by structures 608. In this example, lower surface 640 is thickerat regions away from structures 608 while lower surface 642 is thinnerat structures 608. In this example, thermal runaway mitigation regionsmay span lower surface 642 at structures 608. In this example, thethickness difference between lower surface 640 and at 642 may be createdthrough various techniques, including, for example, laminating a layerof the same or different material over the bottom of cooling plate 636.In this example, material at locations corresponding to structures 608is removed from the laminating sheet before or after laminating. In thisexample, the laminating sheet may include holes or voids in the sheetthat correspond to the structures 608.

Cutaway view (6) shows a cooling plate 644 with cooling channels 606formed by structures 608. In this example, lower surface 646 is thickerat regions away from structures 608 while lower surface 648 is thinnerat structures 608. In this example, thermal runaway mitigation regionsmay span lower surface 646 at structures 608. In this example, thethickness difference between lower surface 646 and at 648 may be createdthrough various techniques, including, for example, throughhydroforming, welding, additive manufacturing, or other materialdeposition techniques.

Cutaway view (7) shows a cooling plate 650 with cooling channels 606formed by structures 608 between an upper surface 652 and lower surface654. In this example, lower surface 654 is made of a different materialthan upper surface 652. In some examples, upper surface 652 may be madefrom a first material and lower surface 654 may be made from a secondmaterial, where for example, the second material may have a lowermelting point than the first material. In this example, thermal runawaymitigation regions may span lower surface 654. In some examples, thefirst material may be a steel or steel alloy, while the second materialmay be aluminum or an aluminum alloy.

FIG. 6C shows a perspective view of an illustrative thermal runawaymitigation region formation 656. For example, layer 658 containing oneor more surface features 660, may be laminated to a solid layer 662. Inthis example, layer 658 may include a plurality of features 660 wherethe features 660 may be voids, holes, apertures, fissures, openings,split, slit, rift, cut, cleft, discontinuity, or thinned areas. Features660 may be dispersed across layer 658 in a uniform or random pattern. Inexamples, features 660 may be located on layer 658 to correspond withcells contained in a battery module or features on a cooling plate, suchas structures 608 or structures 610. In examples, features 660 may belocated on layer 658 to correspond to the inverse of cells contained ina battery module or features on a cooling plate, such as structures 608or structures 610.

FIG. 7 shows a portion of an illustrative autonomous vehicle 700 withbattery pack 702 visible. In this illustrative example, battery pack 702includes six battery modules (not shown). Battery pack 702 may alsoinclude vents 704 on a side 706 of casing 708. In examples, vents 704may be configured to selectively open to allow pressure inside batterypack 702 to equalize, for example to atmospheric pressure. Additionallyor alternatively, examples include vents 704 selectively opening toallow gas, active material, and/or coolant to exit battery pack 702through one or more of vents 704 during a thermal runaway event. In thisillustrative configuration, gas, active material, and/or coolant mayexit vent 704 in direction 710 with significant energy that could causedamage to people and/or structures located in its path.

FIG. 8 shows autonomous vehicle 700 with battery pack 702 fitted withheat shield 800. In this illustrative example, heat shield 800 maydirect gas, active material, and/or coolant passing through vents 704 indirection 802. In examples, heat shield 800 may form a baffle. This maycause a change in direction of the gas, active material, and/or coolantand may reduce the overall energy thereof and/or direct the gas, activematerial, and/or coolant in a safer direction when compare to direction710.

Example Methods and Processes

FIGS. 9-10 are flowcharts showing example methods and processesinvolving vehicles having batteries and cooling systems. The methodsillustrated in FIGS. 9-10 are described with reference to one or more ofthe vehicles, batteries, and/or systems shown in FIGS. 1-8 forconvenience and ease of understanding. However, the methods andprocesses illustrated in FIGS. 9-10 are not limited to being performedusing the vehicles, batteries, and/or systems shown in FIGS. 1-8, andmay be implemented using any of the other vehicles, batteries, and/orsystems described in this application, as well vehicles, batteries,and/or systems other than those described herein. Moreover, thevehicles, batteries, and/or systems described herein are not limited toperforming the methods and processes illustrated in FIGS. 9-10.

FIG. 9 depicts an example process 900 of mitigating a thermal runawayevent. At operation 902, a battery pack, experiences a thermal runawayevent in one or more cells of one or more battery modules.

At operation 904, the battery model containing the cells experiencingthe thermal runaway event allows gas and/or active material to passthrough a frangible top of the battery module. The gas and/or activematerial passes into a gap between the battery module experiencing thethermal runaway event and a battery module directly above.

At operation 906, the thermal runaway event triggers thermal runawaymitigation regions based on gas and/or active material impinging on asurface of cooling plate. For example, if the gas and/or active materialexceeds an energy threshold, the impingement will trigger the thermalrunaway mitigation regions.

At operation 908, the triggered thermal runaway mitigation regionsbreach the cooling exposing coolant from cooling channels of the coolingplate.

At operation 910, the triggered thermal mitigation regions expel coolantfrom cooling channels though breach toward the gas and/or activematerial and/or cells experiencing thermal runaway. For example, theexpelled coolant may mix with the gas and/or active coolant to reducethe temperature and/or kinetic energy of the gas and/or active material.

At operation 912, the gas, active material, and/or coolant activate oneor more vents based at least in part on a pressure change caused by thegas, active material, and/or expelled coolant. For example, gas and/oractive material released from a cell during a thermal runaway event willoften create an increase in pressure within the battery pack. Thisincrease in pressure may activate the vent. In examples, coolantexpelled from the cooling channels during a thermal runaway event willoften create an increase in pressure within the battery pack. Thisincrease in pressure may activate the vent.

At operation 914, the gas, active material, and/or expelled coolantevacuate battery pack through the gap between the battery modules andthrough the activated vent. For example, the pressure increase caused bythe gas and/or active material and the pressure increase caused by theexpelled coolant, may cause a flow of the gas, active material, and/orexpelled coolant out of the battery pack.

FIG. 10 depicts an example process 1000 of mitigating a thermal runawayevent. At operation 1002, a system, for example, vehicle, a drivemodule, a computer system, or combinations thereof, controls a coolingsystem. In examples, the cooling system comprises a heating ventilationand air conditioning system to cool a passenger compartment of avehicle. In examples, the cooling system comprises a coolant, forexample, a liquid coolant, a coolant reservoir, valves, control system,or combinations thereof.

At operation 1004, the system detects a trigger. For example, a triggermay be indicative of a thermal runaway event occurring in a cell of abattery. In examples, a thermal runaway event is experienced in one ormore cells of a battery pack. In examples, the thermal runaway event mayhave multiple stages. For example, a cell may experience a thermalrunaway event causing an internal temperature of the cell to increase toan over temperature condition. In examples, the over temperaturecondition may indicate that a cell will, is, and/or has expelled and/orvented gas and/or active material from the cell.

Additionally or alternatively, in examples, the trigger may include achange in temperature, a change in pressure, or a combination thereof.For example, a change in temperature may include a change in a batterytemperature, a coolant temperature, or a combination thereof. Inexamples, the coolant temperature is measured at a coolant outlet of thebattery, a coolant return of the cooling system, or a combinationthereof. In examples the battery temperature is measured at an externalsurface of a battery module an internal surface of a battery module, anembedded location in a potting material of a battery module, an insidesurface of a battery case, an outside surface of a battery casing, aninternal surface of a battery casing.

In some examples, the change in temperature is above a temperatureincrease threshold. In some examples, the change in temperature is abovea temperature increase threshold for a duration greater than a thresholdtemperature period. In this example, the temperature being above atemperature increase threshold for greater than a time limit may help tofilter sensor noise and/or reduce false triggers.

Additionally or alternatively, in some examples, the change in pressureincludes a decrease in pressure of the coolant or coolant system. Inthis example, a decrease in pressure may indicate that the cell hasentered thermal runaway and has breached a surface of a cooling platecausing coolant to be expelled from the cooling plate and mixing withgas and/or active material vented from the cell and/or douse the cell.These interactions may mitigate the thermal runaway event.

Additionally or alternatively, in some examples, the change in pressureincludes an increase in pressure. In this example, the increase inpressure may be caused by a phase change (e.g., boiling) of the coolant.In this example, the coolant may be heated by the cell causing thecoolant to boil and expand. In examples, this may occur before adecrease in pressure is detected, for example, due to a breach in thecooling plate.

Additionally or alternatively, the detecting a trigger may includedetecting a thermal mitigation event. For example, the thermalmitigation event may include detecting that a cooling plate has beenbreach and is expelling coolant on the cell experiencing a thermalrunaway event, activity, and/or condition.

At operation 1006, the system increases, based at least in part ondetecting the trigger, a level of cooling capacity provided to the cell.In examples, the increase of cooling includes increasing a flowrate ofcoolant to the cell, reducing a temperature of coolant provided to thecell, or combinations thereof.

For example, at operation 1008, the system increases a flowrate ofcoolant to the cell through a first cooling plate below the cell, asecond cooling plate above the cell, or a combination thereof. Inexamples, the increased coolant flow may pull heat from the cell throughthe first cooling plate below the cell. In examples, the second coolingsheet may expel coolant on to or into the vicinity of the cell tomitigate the thermal runaway event. In examples, the increased flowratemay be effected by increasing the pressure of the coolant system.

Additionally or alternatively, at operation 1010, the system lowers atemperature of the coolant directed to the cell. In this example, thesystem may cause the coolant temperature to drop to a lower temperatureand a normal coolant temperature. This lower temperature may allow thecoolant to absorb additional energy when compared to the coolant at anormal coolant temperature.

Additionally or alternatively, the system may cause another coolingsystem, for example, a cooling system contained in a drive moduleseparate from the battery containing the cell, to provide coolant to thecell. In this example, the other cooling system may adjust the coolantflowrate and/or coolant temperature similar to the cooling systemdescribe above.

At operation 1012, the system may continue to provide coolant to thecell, for example, by discharging coolant. In examples, the coolant maybe supplied from a coolant reservoir. In some examples, the system maydischarge the coolant until the coolant reservoir is depleted. Inexamples, a thermal runaway event may cause the vehicle to not besuitable to transport passengers until the battery is replaced and/orrepaired. In this case, it may be desirable to use the coolant availableto mitigate the thermal runaway event and not reserve coolant for futureoperation of the HVAC system.

The methods and processes 900 and 1000 are illustrated as collections ofblocks in logical flow graphs, which represent sequences of operationsthat can be implemented in hardware, software, or a combination thereof.In the context of software, the blocks represent computer-executableinstructions stored on one or more computer-readable storage media that,when executed by one or more processors, perform the recited operations.Generally, computer-executable instructions include routines, programs,objects, components, data structures, and the like that performparticular functions or implement particular abstract data types. Theorder in which the operations are described is not intended to beconstrued as a limitation, and any number of the described blocks can becombined in any order and/or in parallel to implement the processes. Insome embodiments, one or more blocks of the process may be omittedentirely. Moreover, the methods and processes 900 and 1000 may becombined in whole or in part with each other or with other methods.

The various techniques described herein may be implemented in thecontext of computer-executable instructions or software, such as programmodules, that are stored in computer-readable storage and executed bythe processor(s) of one or more computers or other devices such as thoseillustrated in the figures. Generally, program modules include routines,programs, objects, components, data structures, etc., and defineoperating logic for performing particular tasks or implement particularabstract data types.

Other architectures may be used to implement the describedfunctionality, and are intended to be within the scope of thisdisclosure. Furthermore, although specific distributions ofresponsibilities are defined above for purposes of discussion, thevarious functions and responsibilities might be distributed and dividedin different ways, depending on circumstances.

Similarly, software may be stored and distributed in various ways andusing different means, and the particular software storage and executionconfigurations described above may be varied in many different ways.Thus, software implementing the techniques described above may bedistributed on various types of computer-readable media, not limited tothe forms of memory that are specifically described.

Example Clauses

Any of the example clauses in this section may be used with any other ofthe example clauses and/or any of the other examples or embodimentsdescribed herein.

A. A vehicle comprising: a cooling system having a coolant; and abattery system comprising: a first battery module comprising: a firstplurality of energy storage cells; and a cooling element disposed belowthe first plurality of energy storage cells, the cooling element influid communication with the cooling system; and a second battery modulecomprising: a second plurality of energy storage cells, the secondbattery module being disposed below the first battery module such that acell of the second plurality of energy storage cells is disposed belowthe cooling element, wherein the cooling element is configured, inresponse to the cell entering thermal runaway, to expel coolant onto thecell.

B. The vehicle as paragraph A recites, wherein the cooling elementcomprises a cooling plate, the cooling plate comprising: a first surfacehaving a first thickness, the first surface disposed adjacent to thefirst plurality of energy storage cells; and a second surface having asecond thickness, the second surface opposite the first surface, and thesecond thickness being thinner than the first thickness.

C. The vehicle as any one of paragraphs A or B recites, wherein thecooling element comprises a cooling plate, the cooling plate comprising:a first surface disposed adjacent to the first plurality of energystorage cells; and a second surface comprising a first area and a secondarea, the second area being thinner than the first area.

D. The vehicle as any one of paragraphs A-C recites, wherein the secondsurface comprises a first sheet of material bonded to a second sheet ofmaterial, the second sheet of material having a void corresponding tothe second area.

E. The vehicle as any one of paragraphs A-D recites, wherein the coolingelement comprises a cooling plate, the cooling plate comprising: a firstsurface comprising a first material, the first surface disposed adjacentto the first plurality of energy storage cells; and a second surface,including a second material, the second surface opposite the firstsurface, and the first material having a higher melting temperature thanthe second material.

F. The vehicle as any one of paragraphs A-E recites, wherein the coolingsystem comprises a heating ventilation and air conditioning system tocool a passenger compartment of the vehicle.

G. The vehicle as any one of paragraphs A-F recites, further comprising:a second a cooling system; and a second battery system, the secondcooling system in fluid communication with the second battery system,and in fluid communication with the cooling system.

H. The vehicle as any one of paragraphs A-G recites, wherein the secondbattery module further comprising a heat shield disposed above thesecond plurality of energy storage cells, the heat shield beingfrangible and configured to breach in response to the cell enteringthermal runaway.

I. The vehicle as any one of paragraphs A-H recites, wherein the secondbattery module comprises at least one of a valve or a trough to directcoolant expelled from cooling channel to exit the battery system afterbeing expelled onto the cell.

J. A battery system comprising: a first battery module comprising: afirst plurality of energy storage cells; and a cooling element disposedbelow the first plurality of energy storage cells, the cooling elementcontaining coolant; and a second battery module comprising: a secondplurality of energy storage cells, the second battery module beingdisposed below the first battery module such that a cell of the secondplurality of energy storage cells is disposed below the cooling element,wherein the cooling element is configured, in response to the cellentering thermal runaway, to expel coolant onto the cell.

K. The battery system as paragraph J recites, wherein the coolingelement comprises a cooling plate, the cooling plate comprising: a firstsurface having a first thickness, the first surface disposed adjacent tothe first plurality of energy storage cells; and a second surface havinga second thickness, the second surface opposite the first surface, andthe second thickness being thinner than the first thickness.

L. The battery system as any one of paragraphs J or K recites, whereinthe cooling element comprises a cooling plate, the cooling platecomprising: a first surface disposed adjacent to the first plurality ofenergy storage cells; and a second surface comprising a first area and asecond area, the second area being thinner than the first area.

M. The battery system as any one of paragraphs J-L recites, wherein thesecond surface comprises a first sheet of material bonded to a secondsheet of material, the second sheet of material having a voidcorresponding to the second area.

N. The battery system as any one of paragraphs J-M recites, wherein thecooling element comprises a cooling plate, the cooling plate comprising:a first surface comprising a first material, the first surface disposedadjacent to the first plurality of energy storage cells; and a secondsurface, including a second material, the second surface opposite thefirst surface, and the first material having a higher meltingtemperature than the second material.

O. The battery system as any one of paragraphs J-N recites, wherein thesecond battery module further comprises a heat shield disposed above thesecond plurality of energy storage cells, the heat shield beingfrangible and configured to breach in response to the cell enteringthermal runaway.

P. The battery system as any one of paragraphs J-O recites, wherein thesecond battery module comprises at least one of a valve or a trough todirect coolant expelled from cooling channel to exit the battery systemafter being expelled onto the cell.

Q. A thermal runaway mitigation system, comprising: a plurality ofenergy storage cells; and a cooling element disposed above the pluralityof energy storage cells such that a cell of the plurality of energystorage cells is disposed below the cooling element, the cooling elementcontaining coolant, wherein the cooling element is configured, inresponse to the cell entering thermal runaway, to expel coolant onto thecell.

R. The thermal runaway mitigation system as paragraph Q recites, whereinthe cooling element comprises a cooling plate, the cooling platecomprising: a first surface having a first thickness; and a secondsurface having a second thickness, the second surface opposite the firstsurface and disposed between the first surface and the cell, and thesecond thickness being thinner than the first thickness. The thermalrunaway mitigation system of claim 17, wherein the cooling elementcomprises a cooling plate, the cooling plate comprising: a firstsurface; and a second surface, the second surface opposite the firstsurface and between the first surface and the cell, the second surfacecomprising a first area and a second area, the second area being thinnerthan the first area.

S. The thermal runaway mitigation system as any one of paragraphs Q or Rrecites, wherein the cooling element comprises a cooling plate, thecooling plate comprising: a first surface comprising a first material;and a second surface including a second material, the second surfaceopposite the first surface and disposed between the first surface andthe cell, and the first material having a higher melting temperaturethan the second material.

T. A battery architecture comprising cooling plates configured to failat localized regions above a cell that has entered thermal runaway inorder direct coolant onto the failed cell to quench the failed cell andprevent it from causing other nearby cells from entering thermal runawayand starting a chain reaction.

U. A battery architecture comprising a heat shield disposed above abattery module and configured to break at a localized region above eachcell, and in the event that a cell enters thermal runaway, hot gasand/or active material ejected from the cell break through the heatshield and are directed into a space between the heat shield and acooling plate and away from other adjacent cells.

V. A battery system comprising: a first battery module comprising: afirst module housing including a bottom surface; and a first pluralityof energy storage cells disposed in the housing; and a second batterymodule disposed below the first battery module, the second batterymodule comprising: a second module housing; a second plurality of energystorage cells disposed in the second module housing; and a heat shielddisposed in the second module housing above the second plurality ofenergy storage cells, at least a portion of the heat shield disposedabove a cell of the second plurality of energy storage cells andconfigured to break in response to material exhausted from the cell tovent the material from the cell into a space between the first modulehousing and the second module housing.

W. The battery system as paragraph V recites, the heat shield comprisinga thermal runaway mitigation feature comprising at least one of a regionof the heat shield that is weaker than another region of the heatshield, or region of the heat shield that is thinner than another regionof the heat shield.

X. The battery system as any one of paragraphs V or W recites, the heatshield comprising a thermal runaway mitigation feature, the heat shieldcomprising: a first layer having an aperture; and a second layerlaminated to the first layer, the aperture of the first layer definingthe thermal runaway mitigation feature.

Y. The battery system as any one of paragraphs V-X recites, furthercomprising a casing including a valve configured to open in response toan increase in pressure in the casing caused by the cell exhaustingmaterial into the casing to vent the material from the casing.

Z. The battery system as any one of paragraphs V-Y recites, the heatshield comprising a frangible material that, when breached during thethermal runaway event, shields the second plurality of energy storagecells from heat of the material exhausted from the cell.

AA. The battery system as any one of paragraphs V-Z recites, wherein thefrangible material comprising mica, phlogopite, muscovite, ceramic, or acombination thereof.

BB. The battery system as any one of paragraphs V-AA recites, furthercomprising a battery pack casing at least partially enclosing the firstmodule housing and the second module housing, the battery pack casingcomprising an exhaust vent and an exhaust shield disposed over theexhaust vent to direct the material exhausted from the cell away from apassenger compartment of a vehicle.

CC. The battery system as any one of paragraphs V-BB recites, whereinone or more of the heat shield has a thickness of at least about 1 mmand at most about 3 mm, or the heat shield is spaced at most about 5 mmmillimeters above a top surface of the second plurality of energystorage cells.

DD. A battery module comprising: a module housing, the module housingcomprising one or more supports protruding from the module housing tocouple the module housing to a casing of a battery pack; a plurality ofenergy storage cells disposed in the module housing; and a heat shielddisposed in the module housing above the plurality of energy storagecells, at least a portion of the heat shield disposed above a cell ofthe plurality of energy storage cells and configured to break inresponse to material exhausted from the cell to vent the material fromthe cell into a battery module bay bounded at least in part by thesupports protruding from the module housing.

EE. The battery module as paragraph DD recites, the heat shieldcomprising a thermal runaway mitigation feature comprising at least oneof a region of the heat shield that is weaker than another region of theheat shield, or region of the heat shield that is thinner than anotherregion of the heat shield.

FF. The battery module as any one of paragraphs DD or EE recites, theheat shield comprising a thermal runaway mitigation feature, the heatshield comprising: a first layer of a material containing a hole; and asecond layer of the material laminated to the first layer, the hole ofthe first layer defining the thermal runaway mitigation feature.

GG. The battery module as any one of paragraphs DD-FF recites, the heatshield comprising a frangible material that, when breached during thethermal runaway event, shields the plurality of energy storage cellsfrom heat of the material exhausted from the cell, the frangiblematerial comprising mica, phlogopite, muscovite, ceramic, or acombination thereof.

HH. The battery module as any one of paragraphs DD-GG recites, whereinthe battery module is a first battery module and the battery module bayis a first battery module bay, and the supports protruding from themodule housing restrict passage of air between the first battery modulebay and a second battery module bay associated with a second batterymodule disposed above or below the first battery module, therebythermally insulating the first battery module bay from the secondbattery module bay.

II. A battery pack comprising: a first battery module comprising a firstplurality of energy storage cells; and a second battery module disposedbelow the first battery module, the second battery module comprising: asecond plurality of energy storage cells; and a heat shield disposedabove the second plurality of energy storage cells, the heat shieldincluding a thermal runaway mitigation feature disposed above a cell ofthe second plurality of energy storage cells and configured to break inresponse to material exhausted from the cell to vent the material fromthe cell into a space between the first module and the second module.

JJ. The battery pack as paragraph II recites, the thermal runawaymitigation feature comprising at least one of a region of the heatshield that is weaker than another region of the heat shield, or regionof the heat shield that is thinner than another region of the heatshield.

KK. The battery pack as any one of paragraphs II or JJ recites, the heatshield comprising: a first layer having an aperture; and a second layerlaminated to the first layer, the aperture of the first layer definingthe thermal runaway mitigation feature.

LL. The battery pack as any one of paragraphs II-KK recites, the secondbattery module including a valve configured to open in response to thecell exhausting material to vent the material from the second batterymodule.

MM. The battery pack as any one of paragraphs II-LL recites, wherein oneor more of the heat shield has a thickness of at least about 1 mm and atmost about 3 mm, or the heat shield is spaced at most about 5 mmmillimeters above a top surface of the second plurality of energystorage cells.

NN. The battery pack as any one of paragraphs II-MM recites, wherein thefrangible material comprising mica, phlogopite, muscovite, ceramic, or acombination thereof.

OO. The battery pack as any one of paragraphs II-NN recites, furthercomprising a battery pack casing at least partially enclosing the firstbattery module and the second battery module, the battery pack casingcomprising an exhaust vent and an exhaust shield disposed over theexhaust vent to direct the material exhausted from the cell away from apassenger compartment of a vehicle.

PP. A cooling system architecture comprising sensors, cooling elements,and controls configured to detect a trigger indicating that a cell thathas entered thermal runaway and respond by cooling coolant to a lowertemperature and/or provide additional coolant to the battery containingthe failed cell to prevent it from causing other nearby cells fromentering thermal runaway and starting a chain reaction.

QQ. A vehicle comprising: a cooling system having a coolant, the coolingsystem comprising a heating ventilation and air conditioning system tocool a passenger compartment of the vehicle; a battery comprising a cellfor storing energy; and a computer system comprising: one or moreprocessors; and memory storing one or more computer-executableinstructions that are executable by the one or more processors toperform operations comprising: controlling the cooling system to coolthe battery of the vehicle; detecting a trigger associated with adischarge of coolant from the cooling system to mitigate a thermalrunaway event in a cell of the battery of the vehicle; and increasing,based at least in part on detecting the trigger, a level of coolingcapacity provided to the cell.

RR. The vehicle as paragraph QQ recites, wherein the increasing thelevel of cooling comprises at least one of increasing a flowrate ofcoolant to the battery or reducing a temperature of coolant provided tothe battery.

SS. The vehicle as any one of paragraphs QQ or RR recites, wherein theincreasing the level of cooling comprises increasing a flowrate ofcoolant to at least one of a first cooling plate below the cell or asecond cooling plate above the cell.

TT. The vehicle as any one of paragraphs QQ-SS recites, wherein theincreasing the level of cooling comprises reducing a temperature ofcoolant provided to at least one of a first cooling plate below the cellor a second cooling plate above the cell.

UU. The vehicle as any one of paragraphs QQ-TT recites, furthercomprising another cooling system, wherein the increasing the level ofcooling comprises directing coolant from the other cooling system to thebattery.

VV. The vehicle as any one of paragraphs QQ-UU recites, wherein thetrigger comprises at least one of a change in temperature or a change inpressure of at least a portion of the cooling system.

WW. The vehicle as any one of paragraphs QQ-VV recites, wherein thetrigger comprises at least one of a change in temperature or a change inpressure of at least a portion of the battery.

XX. The vehicle as any one of paragraphs QQ-WW recites, whereindetecting a trigger includes detecting a discharge of coolant to a cellof the battery.

YY. A method comprising: controlling a cooling system to provide coolantto cool a battery of a vehicle; detecting a trigger associated with adischarge of coolant from the cooling system to mitigate an overtemperature condition of the battery of the vehicle; and increasing,based at least in part on detecting the trigger, a level of coolingcapacity provided to the battery by the coolant.

ZZ. The method as paragraph YY recites, wherein the increasing the levelof cooling capacity comprises at least one of increasing a flowrate ofthe coolant to the battery or reducing a temperature of the coolantprovided to the battery.

AAA. The method as any one of paragraphs YY or ZZ recites, wherein theincreasing the level of cooling capacity comprises increasing a flowrateof coolant to at least one of a first cooling plate below a cell of thebattery or a second cooling plate above the cell of the battery.

BBB. The method as any one of paragraphs YY-AAA recites, wherein theincreasing the level of cooling capacity comprises reducing atemperature of coolant provided to at least one of a first cooling platebelow a cell of the battery or a second cooling plate above the cell ofthe battery.

CCC. The method as any one of paragraphs YY-BBB recites, wherein theincreasing the level of cooling capacity comprises directing coolantfrom another cooling system to the battery.

DDD. The method as any one of paragraphs YY-CCC recites, wherein thetrigger comprises at least one of a change in temperature or a change inpressure of at least a portion of the cooling system.

EEE. The method as any one of paragraphs YY-DDD recites, wherein thetrigger comprises at least one of a change in temperature or a change inpressure of at least a portion of the of the battery.

FFF. The method as any one of paragraphs YY-EEE recites, whereindetecting a trigger includes detecting a discharge of coolant to a cellof the battery.

GGG. One or more non-transitory computer-readable media storinginstructions configured for execution by one or more processors of acomputing system to perform actions comprising: controlling a coolingsystem to provide coolant to cool a battery of a vehicle; detecting atrigger associated with a discharge of coolant from the cooling systemto mitigate an over temperature condition of the battery of the vehicle;and increasing, based at least in part on detecting the trigger, a levelof cooling capacity provided to the battery by the coolant.

HHH. The one or more non-transitory computer-readable media as paragraphGGG recites, wherein the increasing the level of cooling capacitycomprises at least one of increasing a flowrate of coolant to thebattery or reducing a temperature of coolant provided to the battery.

III. The one or more non-transitory computer-readable media as any oneof paragraphs GGG or HHH recites, wherein the increasing the level ofcooling capacity comprises directing coolant from another cooling systemto the battery.

JJJ. The one or more non-transitory computer-readable media as any oneof paragraphs GGG-III recites, wherein the trigger comprises at leastone of a change in temperature or a change in pressure of at least aportion of the cooling system or at least a portion of the battery.

While the example clauses described above are described with respect toone particular implementation, it should be understood that, in thecontext of this document, the content of the example clauses may also beimplemented via a method, device, system, a computer-readable medium,and/or another implementation.

CONCLUSION

While one or more examples of the techniques described herein have beendescribed, various alterations, additions, permutations and equivalentsthereof are included within the scope of the techniques describedherein.

In the description of examples, reference is made to the accompanyingdrawings that form a part hereof, which show by way of illustrationspecific examples of the claimed subject matter. It is to be understoodthat other examples can be used and that changes or alterations, such asstructural changes, can be made. Such examples, changes or alterationsare not necessarily departures from the scope with respect to theintended claimed subject matter. While the steps herein may be presentedin a certain order, in some cases the ordering may be changed so thatcertain inputs are provided at different times or in a different orderwithout changing the function of the systems and methods described. Thedisclosed procedures could also be executed in different orders.Additionally, various computations that are herein need not be performedin the order disclosed, and other examples using alternative orderingsof the computations could be readily implemented. In addition to beingreordered, the computations could also be decomposed intosub-computations with the same results.

What is claimed is:
 1. A battery system comprising: a first batterymodule comprising: a first module housing including a bottom surface;and a first plurality of energy storage cells disposed in the housing;and a second battery module disposed below the first battery module, thesecond battery module comprising: a second module housing; a secondplurality of energy storage cells disposed in the second module housing;and a heat shield disposed in the second module housing above the secondplurality of energy storage cells, the heat shield comprising: athermally insulating and frangible material; and a first layer bondedwith a second layer, wherein the first layer defines at least oneaperture and has a uniform thickness surrounding the at least oneaperture and the second layer has a uniform thickness, at least aportion of the heat shield disposed above a cell of the second pluralityof energy storage cells and configured to break at the aperture inresponse to material exhausted from the cell to vent the material fromthe cell into a space between the first module housing and the secondmodule housing.
 2. The battery system of claim 1, further comprising acasing including a valve configured to open in response to an increasein pressure in the casing caused by the cell exhausting material intothe casing to vent the material from the casing.
 3. The battery systemof claim 2, wherein the thermally insulating and frangible materialcomprises mica, phlogopite, muscovite, ceramic, or a combinationthereof.
 4. The battery system of claim 1, wherein when the heat shieldis breached during a thermal runaway event in which the material isexhausted from the cell, the heat shield shields the second plurality ofenergy storage cells from heat of the material exhausted from the cell.5. The battery system of claim 1, further comprising a battery packcasing at least partially enclosing the first module housing and thesecond module housing, the battery pack casing comprising an exhaustvent and an exhaust shield disposed over the exhaust vent to direct thematerial exhausted from the cell away from a passenger compartment of avehicle.
 6. The battery system of claim 1, wherein one or more of theheat shield has a thickness of at least about 1 mm and at most about 3mm, or the heat shield is spaced at most about 5 mm millimeters above atop surface of the second plurality of energy storage cells.
 7. Thebattery system of claim 1, wherein the first layer comprises mica andthe second layer comprises mica.
 8. The battery system of claim 1, thefirst battery module further comprising a cooling plate disposed at thebottom surface to regulate thermal characteristics of the first batterymodule, the heat shield of the second battery module and the coolingplate defining the space between the first module housing and the secondmodule housing and providing a passageway for the material exhaustedfrom the cell to vent away from the battery system.
 9. A battery modulecomprising: a module housing, the module housing comprising one or moresupports protruding from the module housing to couple the module housingto a casing of a battery pack; a plurality of energy storage cellsdisposed in the module housing; and a heat shield disposed in the modulehousing above the plurality of energy storage cells, the heat shieldcomprising: a thermally insulating and frangible material; and a firstlayer bonded with a second layer, wherein the first layer defines atleast one aperture and has a uniform thickness surrounding the at leastone aperture and the second layer has a uniform thickness, at least aportion of the heat shield disposed above a cell of the plurality ofenergy storage cells and configured to break in response to materialexhausted from the cell to vent the material from the cell into abattery module bay bounded at least in part by the supports protrudingfrom the module housing.
 10. The battery module of claim 9, wherein whenthe heat shield is breached during a thermal runaway event in which thematerial is exhausted from the cell, the heat shield shields theplurality of energy storage cells from heat of the material exhaustedfrom the cell, the thermally insulating and frangible materialcomprising mica, phlogopite, muscovite, ceramic, or a combinationthereof.
 11. The battery module of claim 10, wherein the battery moduleis a first battery module and the battery module bay is a first batterymodule bay, and the supports protruding from the module housing restrictpassage of air between the first battery module bay and a second batterymodule bay associated with a second battery module disposed above orbelow the first battery module, thereby thermally insulating the firstbattery module bay from the second battery module bay.
 12. The batterymodule of claim 9, wherein the first layer of the heat shield has afirst thickness and the second layer of the heat shield has a secondthickness, the second thickness greater than the first thickness. 13.The battery module of claim 9, wherein the insulating and frangiblematerial comprises at least one of: mica; silicone rubber; teflon;ceramic; aerogel; or combinations thereof.
 14. A battery packcomprising: a first battery module comprising a first plurality ofenergy storage cells; and a second battery module disposed below thefirst battery module, the second battery module comprising: a secondplurality of energy storage cells; and a heat shield disposed above thesecond plurality of energy storage cells the heat shield including athermal runaway mitigation feature comprising a first layer bonded witha second layer, wherein the first layer defines at least one apertureand has a uniform thickness surrounding the at least one aperture andthe second layer has a uniform thickness, the thermal runaway mitigationfeature configured to break at the at least one aperture in response tomaterial exhausted from the cell into a space between the first batterymodule and the second battery module.
 15. The battery pack of claim 14,the second battery module including a valve configured to open inresponse to the cell exhausting material to vent the material from thesecond battery module.
 16. The battery pack of claim 15, wherein thevalve comprises the aperture of the heat shield.
 17. The battery pack ofclaim 14, wherein one or more of the heat shield has a thickness of atleast about 1 mm and at most about 3 mm, or the heat shield is spaced atmost about 5 mm millimeters above a top surface of the second pluralityof energy storage cells.
 18. The battery pack of claim 14, wherein thefirst layer and the second layer of the heat shield comprise aninsulative and frangible material comprising mica, phlogopite,muscovite, ceramic, or a combination thereof.
 19. The battery pack ofclaim 14, further comprising a battery pack casing at least partiallyenclosing the first battery module and the second battery module, thebattery pack casing comprising an exhaust vent and an exhaust shielddisposed over the exhaust vent to direct the material exhausted from thecell away from a passenger compartment of a vehicle.
 20. The batterypack of claim 14, further comprising a cooling plate disposed betweenthe first plurality of energy storage cells and the heat shield of thesecond battery module, the cooling plate configured to release coolantinto the space between the first battery module and the second batterymodule in response to a thermal runaway event of the second batterymodule and to regulate thermal characteristics of the first batterymodule during the thermal runaway event.